The present invention relates a pad clip which is built in a disc brake apparatus of a motor vehicle and which is used to prevent rattling of a backing plate of a pad with respect to a support member during non-braking period, and to prevent the backing plate and the support member from hitting against each other with great force during braking period.
FIG. 1 shows a disc brake apparatus used for braking a motor vehicle. (Note that FIG. 1 shows a disc brake apparatus in which a pad clip according to the present invention is applied, and does not show a prior art.) The disc brake apparatus is fixed to a suspension device with a support member 1 provided adjacent to one side of a rotor (not shown) rotating with a wheel with bolts (not shown) screwed into mounting holes 2, 2 formed in the support member 1 in the radially inward direction of the rotor (lower side in FIG. 1) with respect to the support member 1. The support member 1 supports a caliper 3 so as to be capable of displacing in an axial direction of the rotor (in the direction penetrating a plane of FIG. 1) by engaging a pair of guide pins fixed to the caliper 3 and a pair of guide cylindrical portions (not shown) provided on the support member 1.
A pair of engaging portions 4, 4, is formed on part of the support member 1 at the positions away from each other in a rotational direction of the rotor at both ends with respect to the rotational direction of the rotor. These engaging portions 4, 4 are respectively bent at the extremities thereof into a U-shape so as to straddle the outer periphery of the rotor in the direction penetrating the plane of FIG. 1, and the both ends of a pair of pads 5 provided so as to interpose the rotor is supported by the engaging portions 4, 4. Each pad 5 is formed by adhering a lining 7 to one side of each backing plate 6, and is supported so as to be capable of sliding against the engaging portions 4, 4 in the axial direction of the rotor by allowing engaging projections 8, 8, formed at both ends of the backing plate 6 to engage with engaging grooves 9, 9 formed on the engaging portions 4, 4. Out of both sides of the engaging grooves 9, 9, the radially outer sides thereof with respect to the rotor are partitioned by projections 10, 10 formed so as to project toward the backing plate 6.
The caliper 3 having a cylinder and caliper claws 11 is disposed so as to straddle the pad 5, and is integrally provided with a piston for pressing the pad 5 toward the rotor in the cylinder. Further, pad clips 12, 12 are provided between the outer peripheral edge at both ends of the backing plate 6, which constitutes each pad 5, and the support member 1. Each of these pad clips 12, 12 is formed integrally of a metal plate having resiliency and resistance to corrosion, such as stainless steel plate, and plays a role to prevent generation of a hitting sound, which is referred to as “clonk” during braking period, by preventing the backing plate 6 of each pad 5 from rattling with respect to the support member 1 during non-braking period and preventing the backing plate 6 and the support member 1 from hitting against each other with great force during braking period. The pad clips 12, 12 each have a function to prevent the sliding portion between the respective backing plates 6 and the support member 1 from rusting.
Since the pad clips 12, 12, shown in FIG. 1, belongs to an embodiment of the present invention, a pad clip which is known in the related art will now be described referring to another drawing, FIG. 11. As the pad clip for restraining the hitting sounds, for example, the technologies described in JP-A-08-226473 and JP-A-10-122278 are known in the related art. FIG. 11 shows a pad clip 12a described in JP-A-10-122278 out of those two Patent Documents.
The pad clip 12a shown in FIG. 11 includes a positioning portion 13, a pressing portion 14 and an abutting portion 15. The positioning portion 13 is formed into substantially a C-shape, and engages with the projection 10 formed on part of the support member 1 so as to project toward the backing plate 6 (is fitted onto the projection 10) in order to maintain a positioning of the backing plate in a radial direction of the rotor. The pressing portion 14 is provided in the pad clip in radially inward direction of the rotor (lower side in FIG. 11) with respect to the positioning portion 13. One part (radially outer end in the radial direction of the rotor in the example in the drawing) of a torque transmitting surface 16 for transmitting the braking torque to the support member 1 is resiliently pressed by the end of the backing plate 6 in the rotational direction of the rotor (leftward in the example in the drawing). In addition, the abutting portion 15 is formed on the radially inwardly in the radial direction of the rotor with respect to the pressing portion 14. The abutting portion 15 abuts to one part of a torque receiving surface 17 that is one part of the support member 1 which faces the torque transmitting surface 16. At the radially inner end in the radial direction of the rotor, the extremity of an extending portion 18 formed on a portion continuing from the abutting portion 15 is resiliently abutted against the radially inner peripheral surface of the backing plate 6.
In the case of the pad clip 12a having the structure described above, the positioning portion 13 resiliently clamps the projection 10, and the extremity of the extending portion 18 resiliently abuts against the inner peripheral surface of the backing plate 6, so that rattling of the backing plate 6 with respect to the support member 1 during non-braking period is prevented. Since the pressing portion 14 presses the backing plate 6 in the rotational direction of the rotor, hitting the torque transmitting surface 16 and the torque receiving surface 17 against each other with great force during braking period can be prevented.
In other words, since displacement of the backing plate 6 with respect to the support member 1 is enabled, there exists a space between the both surfaces 16, 17. When the brake is put on, the both surfaces 16, 17 existing in the anchor side (front side in the rotational direction of the rotor) is brought into abutment via one part of the pad clip 12a by a brake torque exerted to the backing plate 6 in association with friction between the side surface of the rotor and the lining 7 (see FIG. 1) adhered on the backing plate 6. In this state, the brake torque exerted on the pad 5 is supported by the support member 1. When the brake is put on, in which the above-described state is resulted, if the torque transmitting surface 16 and the torque receiving surface 17 hit against each other with great force (via pat of the pad clip 12a), the hitting sound  is generated. In contrast, since the pressing portion 14 presses the backing plate 6 in the direction of circumference of the rotor, hitting between the both surfaces 16, 17 is alleviated, and hence generation of hitting sound may be restrained.
Although not shown in the drawing, in JP-A-08-226473, there is shown a structure in which the pressing portion is provided at a radial end in the radial direction of the rotor at the portion deviated from the torque transmitting surface and the torque receiving surface, and the backing plate or the support member is pressed by the pressing portion in the radial direction the rotor. However, in the case of the invention stated in JP-A-08-226473 described above, there is no structure for pressing the backing plate between the torque transmitting surface and the torque receiving surface.
In the case of the structure shown in FIG. 11, it is difficult to increase a force of the pressing portion 14 pressing the backing plate 6 toward the center of the support member 1. Therefore, as in the case in which brake is put on relatively suddenly, when the brake torque exerted to the backing plate 6 during braking period is large, generation of hitting sound cannot be necessarily restrained satisfactorily. In other words, in the case of the structure in the related art shown in FIG. 11, the angle a formed between a pressing strip 22 having the pressing portion 14 and the abutting portion 15 at both ends thereof and the torque transmitting surface 16 and the torque receiving surface 17 is about 1 to 5° in the free state. When pressing the backing plate 6 only by the pressing portion 14 in this structure, the above-described force could not be necessarily increased, and the effect to restrain generation of the hitting sound has not been sure. Such a problem also occurs in the case of the structure described in JP-A-08-226473. When the above-described angle a is increased to about 6 to 10° in the free state, the effect to prevent generation of the hitting sound might increase, but instead, workability in assembling the pad 5 to the support member 1 may be lowered, or resistance generated when the pad 5 slides against the support member 1 increases during braking period and when releasing the brake. Therefore, it is difficult to employ this structure.